Resin-bonded expansion shell

ABSTRACT

A resin reinforced anchor for a rock bolt consists of an expansion shell of a known type modified to mount a resin container. The resin container carries a resin and a hardenercontaining capsule therein in such a way that actuation of the expansion shell breaks the hardener-containing capsule, mixes its contents and the contents of the container, and releases the mixed contents, to adhere the expansion shell to the sides of a drill hole.

United States Patent Cumming [451 Nov. 7, 1972 [541 RESIN-BONDEDEXPANSION SHELL [72] Inventor: James Deans Cumming, Havelock,

Ontario, Canada [22] Filed: Feb. 25, 1971 [21] Appl. No.: 118,843

[52] US. Cl. .,.61/45 B, 52/98, 52/741 [51] Int. Cl. ..E21d 20/02 [58]Field of Search.....61/45 B, 63; 52/98, 698, 704, 52/741, 744; 85/63,65, 72, 79

[56] References Cited UNITED STATES PATENTS 2,829,502 4/1958 Dempsey..61/45 B 2,952,129 9/1960 Dempsey ..61/45 B 3,298,144 1/1967 Fischer..52/98 3,308,585 3/1967 Fischer ..61/45 B X 3,108,443 10/1963Schuermann et al ....52/741 X FOREIGN PATENTS OR APPLICATIONS 1,268,6246/1961 France ..6l/45B 1,245,292 7/1967 Germany ..6l/4SB PrimaryExaminer-Dennis L. Taylor Attorney-Maybee and Legris [5 7 ABSTRACT Aresin reinforced anchor for a rock bolt consists of an expansion shellof a known type modified to mount a resin container. The resin containercarries a resin and a hardener-containing capsule therein in such a waythat actuation of the expansion shell breaks the hardener-containingcapsule, mixes its contents and the contents of the container, andreleases the mixed contents, to adhere the expansion shell to the sidesof a drill hole.

14 Claims, 12 Drawing Figures PAIENTEDnuv 1 1912 3.702.060

sum 1 or 4 INVENTOR JAMES D. CUMMING ATTORNEYS PMENIEDunv 1 I972 SHEET 2BF Q LVVEN'IOR.

JAMES D. CUMMING BY. fad

ATTORNEYS PATENTED V 7 7 sum 3 0F '4 FIG. 8

IN V EN TOR. JAMES D. CUMMING BY% ATTORNEYS PATENTEDuuv' 11912 SHEET '4[IF 4 1x \/E.-\' TOR JAMES 0. CUMMING BY I ATTORNEYS RESIN-BONDEDEXPANSION SHELL BACKGROUND OF THE INVENTION 1. Field of the InventionThis invention relates to rock bolt assemblies and more particularly toan expansion shell assembly which enables an expansion, securing a rockbolt, shell to be securely bonded or adhered in place by a suitablegrout or adhesive.

2. Description of the Prior Art 'The prior art describes several ways inwhich to enhance the gripping, stabilizing and reinforcing effects of arock bolt set and tensioned in a drill hole passing through unstablerock strata. For example, it has been known to pump a cementitious groutmaterial into a drill hole after a rock bolt has been inserted eitherbefore or after the bolt has been tightened to the desired tension. Thispractice tends to bond the entire length of the bolt to the rock stratathrough which it passes and provides for a strong and usually stableinstallation. The practice suffers from the disadvantage that pumps,hoses, grout supplies and fittings must be carried. to the site of eachrock bolt, usually in a mine, and, therefore, under difficultconditions, connected to the rock bolt and the pump operated. Further,grout of this kind frequently requires setting times of several hours.These factors tend to make this type of rock bolt reinforcement timeconsuming and, hence, very expensive.

In other cases, while there is no need to fill the entire drill holewith a grout or other reinforcing material, the nature of the rockstrata, at the expansion shell and which the expansion shell is requiredto grip, may be such that it must itself be reinforced in order tosupport the expansion shell. Other forms of rock strata may be such thatair must be excluded to prevent deterioration of the rock upon exposure,thus eventually weakening it and releasing or partly releasing anyexpansion shell which has been embedded therein.

It is with this latter form of expansion shell bonding that the presentinvention is concerned. That is to say, the present invention isconcerned with the local reinforcement of rock strata adjacent anexpansion shell and with the bonding of the expansion shell theretorather than to the form of reinforcement which requires that the entiredrill hole he filled with a cementitious grout or the like.

Typical of one form of prior an expansion shell assembly for a rock boltin which local reinforcement of the rock strata adjacent the expansionshell is employed is disclosed in the Dempsey US. Pat. No. 2,829,502 ofApr. 5, 1958. In this patent a more or less typical rock bolt andexpansion shell is provided with a capsule which is simply placed uponthe end of the expansion shell which is to be inserted in the drill holeand moved upwardly into the drill hole, resting upon that end of theexpansion shell. A string or wire is secured to the capsule and when itis desired to release the bonding material carried within the capsule,the string is pulled thereby rupturing the capsule and permitting thecontents to escape, flowing downwardly around the expansion shell whereit may set in order to bond the expansion shell to the adjacent rockwall of the drill hole. This construction has two significantdisadvantages. First, the capsule is simply rested upon the end of theexpansion shell and must be carefully introduced into the drill hole bybalancing it upon the end of the expansion shell until both the capsuleand the expansion shell have been inserted in the drill hole. It will beappreciated that this can be a delicate operation in the dark confinesof a mine where the operation must be performed overhead in rathercramped conditions. Secondly, the capsule can be ruptured only bypulling upon the trailing string or wire which extends from the capsulealong the rock bolt leaving an exposed end once the rock bolt has beenset in position. If the string should break, if it should become snaggedor caught upon the rough walls of the drill hole or if it should becometangled during insertion so that an exposed end is not available, theinstallation cannot be completed and the bolt must be withdrawn, a newcapsule substituted and an attempt made again. Clearly, for mineoperations where working conditions are difficult, the device typifiedby the above mentioned Dempsey patent is less than completelysatisfactory.

Another form of construction for a similar purpose is that disclosed inthe Demsey US. Pat. No. 2,952,129 of Sept. 13, 1960. This patentdiscloses an apparatus which eliminates the need for the trailing stringor wire but which requires that the capsule or cannister containing thebonding material be of a frangible substance such as glass which can bebroken by ramming it against the blind end of the drill hole when therock bolt is inserted therein. The disadvantage of this construction is,of course, that the length of the drill hole must be rather nicelycalculated with reference to the length of the rock bolt so that it isshort enough that the capsule can be broken in this manner and yet longenough that the rock bolt may be fully inserted before encountering theblind end of the hole. Further, the use of frangible containers of thekind contemplated by this patent increases the risk of breakage of thesecontainers, accidentally, in handling and installation.

SUMMARY OF THE INVENTION The present invention seeks to provide anexpansion shell which may be bonded and reinforced in its installedposition by a bonding composition which may be carried to theappropriate position, securely fixed upon the end of the expansionshell, protected against accidental breakage and arranged for automaticopening upon the tightening of the rock bolt into its desired conditionof final tension. The present invention does not rely upon the pullingof any trailing strings nor of the breaking of the cannister against theblind end of the drill hole, indeed, the bonding agent capsule may bebroken and activated at any point in the drill hole as conditions mayrequire.

DESCRIPTION OF THE DRAWINGS The invention will be illustrated inconjunction with the accompanying drawings in which like referencenumerals denote like parts in the various views and in which:

FIG. 1 is an axial section through a drill hole, showing an expansionshell embodying the said invention installed therein, a portion of theexpansion shell being shown in longitudinal section;

FIG. 2 is a view similar to FIG. 1 with the rock bolt partly tightened;

FIG. 3 is a view similar to FIGS. 1 and 2 showing the expansion shell inits fully tightened position;

FIG. 4 is a section view taken along line 4-4 of FIG.

FIG. 5 is an exploded fragmentary view showing a portion of theexpansion shell assembly;

FIG. 6 is a view similar to FIGS. 1 and 2 showing the expansion shelland rock bolt in its fully tightened position and illustrating anadditional feature of the invention;

FIG. 7 is a fragmentary view of a modified form of bonding materialcannister;

FIG. 8 is a view similar to FIG. 1 showing an alternative form of theinvention;

FIG. 9 is a view of the device of FIG. 8 in a partly tightenedcondition;

FIG. 10 is a view similar to FIGS. 8 and 9 showing the expansion shellin a fully tightened position;

. FIG. 11 is an exploded view of the expansion shell of FIGS. 8, 9 and10, and

FIG. 12 is a section view along line 12-12 of FIG. 11 with thecomponents of FIG. 11 in their assembled condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the embodimentsillustrated in FIGS. 1 to 7 inclusive, FIGS. 1, 2, 3 and 6 illustrate ablind drill hole 10 formed in rock which it is desired to support andreinforce by means of the rock bolting assemblies illustrated.Typically, the rock within which the drill hole 10 will be formed willbe stratified in nature but the drawings have made no attempt toillustrate this.

A rock bolt 11, typically between 3 feet and 8 feet in length carries anexpansion shell generally indicated at 12 adjacent that end which isinserted in the blind hole. The rock bolt 11 is threaded at 13 and thisend is threadably engaged with the internal threads 14 carried in theaxial bore of a wedge-shaped expander member 15 illustrated in FIG. 5.

Associated with the expander member 15 of the expansion shell are a pairof opposed rock engaging members 16 which are supported by a generallyU-shaped bail 17.

The end of the rock bolt 11 remote from the expansion shell 12 is alsothreaded over a short axial distance at 18 and this threaded portion 18carries a threadably engaged nut 19 lying adjacent an integrally formed,non-circular head 20 formed on that end of the bolt remote from theexpansion shell 12. Also surrounding the rock bolt 11 adjacent thenon-circular head 20 and the nut 18 is a domed, resiliently deformablewasher 21 which is adapted to bear upon the rock face 22 surround thedrill hole 10. The assembly so far described is substantiallyconventional and operates in a conventional manner. In order to insertand secure the rock bolt and its expansion shell within the drill hole10, the rock engaging member 16 are, first, bent outwardly away from theexpander member 15 as shown in FIG. 1 so that the lower skirt portions16a of the rock engaging member 16 will resiliently engage the drillhole and drag along the sides thereof as the bolt is inserted therein.When the bolt has been substantially fully inserted, a slight pull onthe rock bolt in a direction to withdraw it from the hole will drive thewedge 15 between the rock engaging member 16, will cause the rockengaging serrated surfaces to move parallel to the sides of the drillhole and will set the expansion shell in position. A hand or poweroperated wrench is then applied to the non-circular head 20 of the bolt11 and the entire bolt 11 is rotated within the now stationarily heldexpander member 15 thereby drawing it downwardly between the rockengaging member 16 to move firmly seat them and engage them with thewall of the drill hole 10. In conventional rock bolt assemblies, theoperation of installing such an assembly is complete when the bolt 11has been rotated to tighten it to the desired tension.

However, as was explained earlier, some rock conditions require that theexpansion shell be more securely bonded to the drill hole than can beachieved by the simple expansion of the shell as described above.

The present invention provides for this bonding as follows.

The end of the expander member 15 remote from the non-circular head 20on the rock bolt 11 is provided with an axially extending collar 23.Secured to this collar 23 by means such as screw threads (as seen inFIG. 1) or by means of a bayonet joint (as shown at 24 in FIG. 5) is acontainer 25 within which is contained a curable resin compound. Thecontainer 25 may be of plastic or thin sheet metal and is formed, at itslower end 26 with either internal screw threads or internal bayonet lugsto engage the collar 23 of the expander member 15 in order that it maybe mounted in the position shown in FIG. 1. The end of the container 25which is secured to the axially extending collar 23 is sealed by afrangible sealing disc 27. Within the container 25 is a frangiblecapsule 28 containing a curative (accelerator or catalyst) for thecurable resin compound which is within the container 25. The capsule 28is closed at its upper end by a cap 29 and conveniently is made ofplastic or glass having a thinner lower portion 29 as distinct from athicker wall portion 30 so as to ensure its ready breakage as thetightening of the shell proceeds.

Referring to FIG. 1, it can readily be seen that the initial setting ofthe expander member and the rock engaging members by the slight downwardpull on the rock bolt 11 can be achieved with the container 25 and itscontents securely mounted upon the collar 23 of the expander member 15.The position of the container 25 is protected during handling andinstallation of the assembly by the bail 17 which extends upwardly topartially enclose it and protect it from accidental disengagement withthe expander member 15. Further, by reason of its attachment to theexpander member 15 by screw threads or a bayonet joint, cartons ofcontainers 25 may be carried underground in a mine with protectivepackaging and then readily assembled on expansion shells as neededwithout the use of tools.

Turning now to FIG. 2, an intermediate stage in the tightening of theexpansion shell is illustrated. As can be seen in FIG. 2, the expandermember 15 has been drawn downwardly between the rock engaging element 16by rotation of the bolt 11 as a result of the applica tion of a hand orpowered wrench to the non-circular vhead 20. The rotation of the bolt 11within the expansion member 15 has resulted, as seen in FIG. 2, in theend 11a of the bolt 1 1 having passed axially through the expandermember to first engage and then break the frangible sealing disc 27,fragments of which are shown in FIG. 2 at 27a. Further, the continuedaxial movement of the end 11a of the bolt 11 through the expander memberand into the container has, as illustrated in FIG. 2, resulted in thebreakage of the frangible capsule 28, fragments of which are shown at28a in FIG. 2. The result of this breakage of the frangible capsule andthe rotation of the end 11a of the bolt 11 within the container 25 isthat the curable resin compound and the curative therefor have beenexposed to one another and have been mixed by the turning action of thebolt 1 1 within the container 25.

Turning now to FIG. 3, it can be seen that the continued rotation of thebolt 11 has further advanced the end 11a of the bolt 11 into thecontainer 25 with the result that the end 11a of the bolt 11 has engagedinwardly extending dimples 31 which are provided at circumferentiallyspaced points around the periphery of the container 25. The engagementof the end 1 la of the bolt 1 1 with these dimples 31 has had the effectof forcing the container 25 off the collar 23 of the expander member15.with the result that the mixed contents of the container and thefrangiblecapsule are now permitted to flow downwardly as indicated byarrows 32. This downward flow of the material within the container 25 isarrested by a resilient foam or plastic gasket or a washer 33 so as toconfine the presence of this material to the area immediately around theexpansion shell 12 where it will reinforce the local rock strata, andbond the expansion shell thereto.

Turning back to FIG. 1, it is to be noted that both the container 25 andthe frangible capsule 28 are provided with air spaces 34 andrespectively. In other words, the contents of neither the container 25nor the frangible capsule 28 completely fill these containers.

As is well known in the art, curable resin compositions and hardeners,accelerators, catalysts or curatives therefor can be chemicallycompounded in such a way that almost any form of reaction which isdesired can be obtained. It is desirable, in the context of the presentinvention, that these substances be so chosen that their mixtureinitiates an exothermic reaction which will cause a temperature rise inthe air within the spaces 34 and 35 respectively. In the first stage, asillustrated in FIG. 2, the heated air within the space 35 in thefrangible capsule 28 will result in the expulsion of the curativecontained within the frangible capsule 28 into the main body of thecontainer 25 thereby promoting the intimate mixing of the twocomponents. This mixing will increase the exothermic reaction which willfurther raise the temperature of the air trapped within the space 34with the result that, when as shown in FIG. 3, the container 25 islifted off the collar 23, substantially all of the contents of thecontainer 25 will be expelled therefrom into the area of the expansionshell 12.

Turning now' to FIG. 4, the assemblies of FIGS. 1 to 3 is illustrated inthe finally tightened position with the cured and hardened resincompound substantially surrounding and embedding the expansion shell 12.The cured resincompound is illustrated at reference numeral 36.

I As will be apparent from the description of the function of theapparatus in FIGS. 1 to 3, bolt 11 has been rotated so as to impose atension thereon. The beginning of this can be seen in FIG. 2. In FIG.ll, the

domed, resiliently deformable washer is shown in the position which itoccupies when the bolt 11 is under little or no tension at all. In thisFigure the nut 19 is shown as being engaged with threads 18 and in aposition immediately adjacent the non-circular head 20 of the bolt 11.Rotation of the bolt 11 from the condition of FIG. 1 to the condition ofFIG. 2 has imposed a tension upon the bolt 11 and has caused the washer21 to resiliently deform towards a flattened condition as illustrated inthis FIGURE. Continued rotation of the bolt 11 to produce the effect ofFIG. 3 will further flatten the washer 21 but the washer will not becomecompletely seated upon the face 22 of the rock within which the drillhole 10 has been formed even after the condition of FIG. 3 has beenachieved. I-Iowever, rotation of the bolt 11 will continue until it hasreached, perhaps percent, of the tension which it is intended tosustain. Once the curable resin compound has fully hardened and set asillustrated in FIG. 6, (a period which may range from a few minutes toan hour or so) the nut 19 is then rotated upon the threads 18 in orderto impart additional tension to the bolt 11 and to bring the resilientlydeformable washer 21 to its final, fully flattened position as shown inFIG. 6.

This aspect of the rock bolting assembly illustrated in FIGS. 1 to 7inclusive is a most important aspect of the invention. In the prior rockbolting assemblies making use of expansion shells within which the boltrotates to set and engage the expansion shell, the use of grouts,curable resin compounds and the like rendered the bolt immovable oncethe curing had taken place. In other words, once the tighteningoperation was complete and the bonding or grouting compound had set,further rotation of the bolt was impossible because the bolt could nolonger be rotated within the cured material surrounding the expansionshell. By means of the second nut 19 associated with the non-circularhead 20 of the bolt 11, this defect is completely overcome. As can beseen in FIG. 6, even after the cured compound 36 has rendered furtherrotation of the bolt impossible, the tension of the bolt 11 can beincreased or decreased by simply tightening or slackening the nut 19.This makes it possible, periodically, to adjust the tension of the bolt11 as conditions in the rock strata may require.

While the embodiment of the invention which has been described hereincontemplates that the container 25 will be lifted off the collar 23towards the end of the tightening operation of the bolt 11, it maysometimes occur that the rock strata adjacent the expansion shell are sohard that it is not possible to advance the bolt 11 through the expandermember 15 for an axial extent sufficient for the end 11a of the bolt 11to engage the detents 31 which provide the lifting force to disengagethe container from the collar 23. In this event, the constructionillustrated in FIG. 7 may be adopted.

The modified container 25a of FIG. 7 is identical to the container 25 ofFIGS. 1 to 3 in every respect except that it is provided with an insertring 37 lying beneath the inwardly projecting dimples or lugs 31a. Thering 37 is provided with a central axial aperture 38 and its solefunction is to have the effect of positioning the dimples or lugs 31acloser to the end of the collar 23 of the expander member 15 so that thebolt 11 will not need to travel the same axial extent before engagingthe ring 37 thereby lifting the container 250: off the collar 23 bymeans of which it is mounted upon the expander member 15.

Turning now to FIGS. 8 to 12 inclusive, an expansion shell of similarfunction is disclosed and which is adapted to be used in associationwith an expansion shell which is actuated by a nut on that end remotefrom the expansion shell rotating on bolt 11 without requiring that thebolt 111 rotate within the expander member 115.

Turning first to FIG. 11, the bolt 111 may be seen to be provided with athreaded portion 113 which engages internal threads 114 on awedge-shaped expander member 115. The expander member 115 is providedwith four wedge-shaped surfaces which are adapted to engage four rockengaging elements 116 integrally formed on collar 116a. The expandermember 115 is provided with a U-shaped bail 117 which extends around andsecures a container 125 within which is a frangible capsule 128. The endof the container 125 adjacent the expander member 115 is closed by afrangible sealing disc 127.

Turning now to FIG. 8, it can be seen that the container 125, secured tothe expander member 115 by the bail 117 is provided with a downwardlyextending cylindrical skirt 150 which surroundsand encloses the upperends 11612 of the four rock engaging members 116.

As the nut (not shown) on the threaded end of bolt 111 is tightenedagainst a washer (similar to washer 21 of FIGS. 1, 2 and 3) bearingagainst the rock face within which the drill hole 110 has been formed,the expander member will be drawn downwardly into the expansion shellthereby radially expanding the rock engaging members 116 into firmengagement with the wall of the drill hole 110.

It will be'remembered that the bail 117 secures the container 125 to theexpander member and, accordingly, the expander member will draw thecontainer 125 down into telescoping engagement over and around the fourrock engaging members 116.

As this happens, the result will be as illustrated in FIG. 9. Thefrangible sealing disc 127 will be driven upwardly into the container125 by the upper ends 116b of the rock engaging members 116 and will, asits first act, break the frangible capsule 128 within the container 125.Continued downward movement of the expander member 115, carrying with itthe container 125 will cause the breakage of the frangible seal 127 withthe result that the mixed contents of the frangible capsule 128 and thecontainer 125 will be permitted to flow downwardly as indicated byarrows 132 to surround and bondthe local rock strata to the expansionshell. The downward flow of the material is arrested by the foam orplastic washer 133 (see FIG. 8) in the same manner as has been describedwith reference to the embodiment of FIGS. 1 to 7 inclusive.

Since, in the embodiment of FIGS. 8 to 12 inclusive, the expansion shellis tightened and set within the drill hole 110 by the rotation of a nuton a threaded, free, exposed end of the rock bolt 111, there is no needto provide the post tightening nut corresponding to nut 19 of FIGS. 1, 2and 6. The resin bonded expansion shell will remain fixed in the drillhole and the tension in bolt 111 may be adjusted by rotating thetightening nut in the appropriate direction in a manner which is wellunderstood in the art.

In the embodiment of FIGS. 8 to 12 inclusive it will be noted that boththe container and the frangible capsule 128 are provided with air spaces134 and 135 respectively to provide an expanding air propulsion systemactuated by the exothermic reaction of the mixture of the contents ofthe container and the frangible capsule respectively to expelsubstantially all of the contents of the container 125 when thefrangible seal 127 is broken as illustrated in FIG. 10.

As will be apparent from the foregoing description, the inventionprovides for an expansion shell having a self activating grouting orbonding container associated therewith which suffers from none of thedisadvantages which have been discussed with respect to the prior art.Further, the invention provides for such a bonding or grouting capsuleto be associated with an expansion shell which may be used inassociation with either of the two most commonly used alternativeexpansion shells. The first, being that disclosed in FIGS. 1 to 7inclusive, makes use of an expansion shell which is activated byrotating the entire rock bolt by means of a non-circular head formed onthe end of the bolt which is exposed from the drill hole.

The second embodiment illustrated in FIGS. 8 to 12 inclusive employs anexpansion shell which is actuated by axially drawing the bolt and theexpander member threaded thereon downwardly to the expansion shell bymeans of a nut threaded upon a threaded end of the rock bolt whichextends from the drill hole so that the nut, through the medium of anappropriate washer, may bear uponthe rock space surrounding the drillholeand impart an appropriate tension to the rock bolt.

Further, in the case of the embodiment of FIGS. 1 to 7 inclusive, asecond tightening or tensioning arrangement is provided by means of theauxiliary nut 19 which allows for post hardening adjustment of bolttension in a manner which has not heretofore been possible with a rockbolting assembly of this kind embodying a grouted or bonded expansionshell.

Both embodiments of the present invention have been described herein forillustrative purposes and modifications are contemplated within thescope of the invention and the appended claims.

What I claim is:

1. An expansion shell for a rock bolt adapted to be inserted into ablind hole comprising:

a. at least two opposed rock engaging members;

b. an expander member lying between said at least two rock engagingmembers;

c. a container secured to that end of the expansion shell adjacent theblind end of the hole;

d. a curable resin compound in the container;

e. frangible means sealing the end of the container adjacent theexpansion shell;

f. a frangible capsule in the container;

g. a curative for said curable resin compound in the frangible capsule;

h. and means to cause relative movement between two of i. the rock boltii. the rock engaging members and iii. the expander member thereby tobreak the frangible seal and the capsule thus permitting the curableresin compound and the curative therefor to mix and to escape from thecontainer so as to adhere the expansion shell to the surrounding wall ofthe blind hole.

2. An expansion shell for a rock bolt as claimed in claim 1 wherein thecontainer is secured to the expander member by means of a Ushaped bailenclosing the container within the bight of the U, the free ends of theU-shaped bail being secured to the expander member.

3. An expansion shell for a rock bolt as claimed in claim 2 wherein therelative movement is between the expander member and the rock engagingmembers.

4. An expansion shell for a rock bolt comprising a. at least two opposedrock-engaging members;

b. an expander member lying between said at least two rock-engagingmembers;

c. a container secured to an end of said expander member;

d. frangible means sealing the end of the container adjacent theexpandermember;

e. a curable resin compound in the container;

f. a frangible capsule in the container;

g. a curative for said curable resin compound in the frangible capsule;

h. and means to advance axially through the expander member and, insequence,

- i. break the frangible means sealing the end of the container,

ii. break the frangible capsule within the container,

iii. stir the contents of the container and capsule to mix themtogether, and

iv. disengage the container from the expander member to allow the mixedcontents to escape.

5. An expansion shell for a rock bolt as claimed in claim 4 wherein themeans to advance axially through the expander member is a rock boltthreadably engaged with an axially threaded aperture in the expandermember.

6. An expansion shell for a rock bolt as claimed in claim 4 wherein thecontainer, including its frangible sealing means and its contents areremovably secured to the expander member.

7. An expansion shell for a rock bolt as claimed in claim 6 wherein thecontainer is removably secured to the expander member by a bayonetjoint.

8. An expansion shell for a rock bolt as claimed in claim 6 wherein thecontainer is removably secured to the expander member by a threadedjoint.

9. An expansion shell for a rock bolt as claimed in claim 4 wherein thecontainer has at least two inwardly projecting portions which areengaged by the means to advance axially through the expander memberafter said means has broken the frangible seal on the container, brokenthe frangible capsule and mixed the contents of the container andcapsule together in order to disengage the container from the expandermember and release the mixed contents thereof.

10. An expansion shell for a rock bolt as claimed in claim 4 wherein aprotective yoke of U-shaped configuration is provided, one leg of theyoke being secured to each rock engaging member and extending over theend of the container to offer it protection and guard against accidentaldisplacement thereof.

11. An expansion shell for a rock bolt as claimed in claim 1 wherein a.the container contains an air space;

b. the capsule contains an air space, and

c. the curable resin compound and the curative therefor are selected top ovide an exothermic reaction upon mixing so t at the air in the airspaces is heated to expand and force substantially all of the mixedcontents from the container when it is disengaged from the expandermember.

12. A rock-bolting assembly comprising a. a rock bolt having a firstthreaded end adapted to be inserted in a drill hole in a rock formationand a second threaded end adapted to project therefrom; b. anon-circular head formed on the second end;

c. a nut threaded on said bolt and lying in juxtaposition to saidnon-circular head;

. a washer surrounding the bolt and adapted to bear on the surface ofthe rock formation surrounding the drill hole;

e. and an expansion shell carried by said first threaded end of thebolt, said expansion shell carrying means to release a mixture of acurable resin compound and a curative therefor when said rock boltassembly has been substantially but not entirely fully tightened in thedrill hole.

13. A rock-bolting assembly as claimed in claim 12 including aresilient, deformable washer surrounding the bolt adjacent the expansionshell and in sealing engagement therewith and adapted to lie in sealingengagement with the wall of the drill hole.

14. A rock-bolting assembly as claimed in claim 13 wherein the resilientdeformable washer is of a plastic material.

2. An expansion shell for a rock bolt as claimed in claim 1 wherein thecontainer is secured to the expander member by means of a U-shaped bailenclosing the container within the bight of the U, tHe free ends of theU-shaped bail being secured to the expander member.
 3. An expansionshell for a rock bolt as claimed in claim 2 wherein the relativemovement is between the expander member and the rock engaging members.4. An expansion shell for a rock bolt comprising a. at least two opposedrock-engaging members; b. an expander member lying between said at leasttwo rock-engaging members; c. a container secured to an end of saidexpander member; d. frangible means sealing the end of the containeradjacent the expander member; e. a curable resin compound in thecontainer; f. a frangible capsule in the container; g. a curative forsaid curable resin compound in the frangible capsule; h. and means toadvance axially through the expander member and, in sequence, i. breakthe frangible means sealing the end of the container, ii. break thefrangible capsule within the container, iii. stir the contents of thecontainer and capsule to mix them together, and iv. disengage thecontainer from the expander member to allow the mixed contents toescape.
 5. An expansion shell for a rock bolt as claimed in claim 4wherein the means to advance axially through the expander member is arock bolt threadably engaged with an axially threaded aperture in theexpander member.
 6. An expansion shell for a rock bolt as claimed inclaim 4 wherein the container, including its frangible sealing means andits contents are removably secured to the expander member.
 7. Anexpansion shell for a rock bolt as claimed in claim 6 wherein thecontainer is removably secured to the expander member by a bayonetjoint.
 8. An expansion shell for a rock bolt as claimed in claim 6wherein the container is removably secured to the expander member by athreaded joint.
 9. An expansion shell for a rock bolt as claimed inclaim 4 wherein the container has at least two inwardly projectingportions which are engaged by the means to advance axially through theexpander member after said means has broken the frangible seal on thecontainer, broken the frangible capsule and mixed the contents of thecontainer and capsule together in order to disengage the container fromthe expander member and release the mixed contents thereof.
 10. Anexpansion shell for a rock bolt as claimed in claim 4 wherein aprotective yoke of U-shaped configuration is provided, one leg of theyoke being secured to each rock engaging member and extending over theend of the container to offer it protection and guard against accidentaldisplacement thereof.
 11. An expansion shell for a rock bolt as claimedin claim 1 wherein a. the container contains an air space; b. thecapsule contains an air space, and c. the curable resin compound and thecurative therefor are selected to provide an exothermic reaction uponmixing so that the air in the air spaces is heated to expand and forcesubstantially all of the mixed contents from the container when it isdisengaged from the expander member.
 12. A rock-bolting assemblycomprising a. a rock bolt having a first threaded end adapted to beinserted in a drill hole in a rock formation and a second threaded endadapted to project therefrom; b. a non-circular head formed on thesecond end; c. a nut threaded on said bolt and lying in juxtaposition tosaid non-circular head; d. a washer surrounding the bolt and adapted tobear on the surface of the rock formation surrounding the drill hole; e.and an expansion shell carried by said first threaded end of the bolt,said expansion shell carrying means to release a mixture of a curableresin compound and a curative therefor when said rock bolt assembly hasbeen substantially but not entirely fully tightened in the drill hole.13. A rock-bolting assembly as claimed in claim 12 including aresilient, deformable washer surrounding the bolt adjacent the expansionshell and in sealing engagement therewith and adapted to lie in sealingengagemEnt with the wall of the drill hole.
 14. A rock-bolting assemblyas claimed in claim 13 wherein the resilient deformable washer is of aplastic material.